Smart optical filter for pixel-selectively adjusting light intensity

Abstract

Embodiments provide a smart optical filter capable of dynamically adjusting brightness variations in incident lights in a FOV or an optical field before an image sensor receives the incident lights. The smart optical filter in accordance with the disclosure can be portable and mounted on various imaging devices such as a smart phone or a camera. The smart optical filter may comprises an light adjustment layer made of an adaptive optical materials such liquid crystals. Light intensity distribution can be obtained for an FOV of a device coupled to the smart optical filter. The light intensity distribution can be compared to one or more thresholds to obtain difference values pixels on the light adjustment layer. The difference value can be used to generate control signals to adjust light passing through the pixels. In some embodiments, the control signals may include information indicating an amount of voltage to be applied to the pixels to alter polarization at those pixels.

What is claimed is: 
     
       1. An optical filter for pixel-selectively adjusting light intensity to achieve high dynamic range (HDR) imaging, the optical filter comprising:
 a pre-sensor configured to detect light intensity distribution in a field of view (FOV) of a device in which the optical filter is embedded; 
 a light adjustment layer made of adaptive optical materials, the light adjustment layer comprising a set of pixels, wherein the pixels include a first pixel and a second pixel; 
 a control circuit configured to generate control signals to control adjustment of one or more light transparency levels at the set of pixels based on the light intensity distribution detected by the pre-sensor, wherein the control signals includes a first control signal to control adjustment of a first light transparency level at the first pixel based on the light intensity distribution detected by the pre-sensor and a second control signal to control adjustment of a second light transparency level at a second pixel based on the light intensity distribution detected by the pre-sensor; 
 a driving circuit configured to generate driving signals to control lights passing through the set of pixels based on the control signals generated by the control circuit; and 
 an interface module configured to provide interfacing between the optical filter and the device such that when the device is activated to capture an image, the optical filter is activated to control the adjustment of the light transparency levels at the set of pixels; and, wherein the pre-sensor, the light adjustment layer, the control circuit, and the driving circuit are located within the optical filter. 
 
     
     
       2. The optical filter according to  claim 1 , wherein the adaptive optical materials include one or more of a opto-electrical crystals, dynamic optical polymers, and liquid crystals. 
     
     
       3. The optical filter of  claim 1 , wherein generating the first control signal to control adjustment of the first light transparency level at the first pixel based on the light intensity distribution detected by the pre-sensor comprises:
 obtaining a light intensity value at a first spot in the FOV from the light intensity distribution detected by the pre-sensor, wherein the first spot corresponds to the first pixel; 
 comparing the light intensity value at the first spot with a predetermined threshold; 
 determining a difference value between the light intensity value at the first spot with a predetermined threshold based on the comparison; and 
 generating the first control signal based on the difference value; and, generating the second control signal to control adjustment of the second light transparency level at the second pixel based on the light intensity distribution detected by the pre-sensor comprises: 
 obtaining a light intensity value at a second spot in the FOV from the light intensity distribution detected by the pre-sensor, wherein the second spot corresponds to the second pixel; 
 comparing the light intensity value at the second spot with a predetermined threshold; 
 determining a difference value between the light intensity value at the second spot with a predetermined threshold based on the comparison; and 
 generating the second control signal based on the difference value. 
 
     
     
       4. The optical filter according to  claim 1 , wherein the first control signal includes information indicating a location of the first pixel on the light adjustment layer. 
     
     
       5. The optical filter according to  claim 1 , wherein the driving signals generated by the driving circuit includes a first amount of voltage to be applied to the first pixel and/or a first duration for which the voltage to be applied to the first pixel, and a second amount of voltage to be applied to the second pixel and/or a second duration for which the voltage to be applied to the second pixel, wherein the first amount voltage is separate and distinct from the second voltage. 
     
     
       6. The optical filter according to  claim 1 , wherein the first pixel comprises two polarizers and two electrodes. 
     
     
       7. The optical filter according to  claim 6 , wherein the first control signal indicates to the driving circuit an amount of voltage to be applied to the two electrodes of the first pixel such that the two polarizers are manipulated to block a portion of light passing through the first pixel. 
     
     
       8. The optical filter according to  claim 1 , wherein the set of pixels comprise active matrix pixels divided into columns and rows. 
     
     
       9. The optical filter according to  claim 1 , wherein the interface module comprises a set of mechanical position pins for aligning the optical filter or the filter is electronically registered to the resulted image. 
     
     
       10. The optical filter according to  claim 1 , wherein device is a smart phone and the interface module comprises an electrical interface for coupling the optical filter to the smart phone. 
     
     
       11. The optical filter according to  claim 1 , wherein a temperature of the light adjustment layer is controlled by an embedded electrical heater to avoid malfunction of the optical filter in a cold environment. 
     
     
       12. A method for using an optical filter pixel-selectively to adjust light intensity to achieve high dynamic range (HDR) imaging, wherein the optical filter comprises a pre-sensor, a mechanical or electronic registration, a light adjustment layer, a control circuit, and a driving circuit, wherein the light adjustment layer is made of adaptive optical materials and comprises a set of pixels including a first pixel, the method comprising:
 detecting, using the pre-sensor, a light intensity distribution in a field of view (FOV) of a device in which the optical filter is embedded; 
 generating, by the control circuit, control signals to control adjustment of one or more light transparency levels at the set of pixels based on the light intensity distribution detected by the pre-sensor, wherein the control signals include a first control signal to control adjustment of a first light transparency level at the first pixel based on the detected light intensity distribution and a second control signal to control adjustment of a second light transparency level at a second pixel based on the light intensity distribution detected by the pre-sensor; 
 generating, at the driving circuit, driving signals to control lights passing through the set of pixels based on the control signals; and, wherein the pre-sensor, the light adjustment layer, the control circuit, and the driving circuit are located within the optical filter. 
 
     
     
       13. The method according to  claim 12 , wherein the adaptive optical materials include one or more of a opto-electrical crystals, dynamic optical polymers, and liquid crystals. 
     
     
       14. The method according to  claim 12 , wherein generating the first control signal to control adjustment of the first light transparency level at the first pixel based on the light intensity distribution detected by the pre-sensor comprises:
 obtaining a light intensity value at a first spot in the FOV from the light intensity distribution detected by the pre-sensor, wherein the first spot corresponds to the first pixel; 
 comparing the light intensity value at the first spot with a predetermined threshold; 
 determining a difference value between the light intensity value at the first spot with a predetermined threshold based on the comparison; and 
 generating the first control signal based on the difference value; and, generating the second control signal to control adjustment of the second light transparency level at the second pixel based on the light intensity distribution detected by the pre-sensor comprises: 
 obtaining a light intensity value at a second spot in the FOV from the light intensity distribution detected by the pre-sensor, wherein the second spot corresponds to the second pixel; 
 comparing the light intensity value at the second spot with a predetermined threshold; 
 determining a difference value between the light intensity value at the second spot with a predetermined threshold based on the comparison; and 
 generating the second control signal based on the difference value. 
 
     
     
       15. The method according to  claim 12 , wherein the first control signal includes
 information indicating a location of the first pixel on the light adjustment layer. 
 
     
     
       16. The method according to  claim 12 , wherein the driving signals generated by the driving circuit includes a first amount of voltage to be applied to the first pixel and/or a first duration for which the voltage to be applied to the first pixel, and a second amount of voltage to be applied to the second pixel and/or a second duration for which the voltage to be applied to the second pixel, wherein the first amount voltage is separate and distinct from the second voltage. 
     
     
       17. The method according to  claim 12 , wherein the first pixel comprises two polarizers and two electrodes. 
     
     
       18. The method according to  claim 17 , wherein the first control signal indicates to the driving circuit an amount of voltage to be applied to the two electrodes of the first pixel such that the two polarizers are manipulated to block a portion of light passing through the first pixel. 
     
     
       19. The method according to  claim 12 , wherein the set of pixels comprise active matrix pixels divided into columns and rows. 
     
     
       20. The method according to  claim 12 , wherein device is a smart phone comprising an electrical interface for coupling the optical filter to the smart phone.